Oxidation of sulfided limestone under the conditions of pressurized fluidized bed combustion

✍ Scribed by K. Qiu; E.J. Anthony; L. Jia

• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 901 KB
• Volume: 80
• Category: Article
• ISSN: 0016-2361
• DOI: 10.1016/s0016-2361(00)00128-9

✦ Synopsis

During coal gasification, the removal of H 2 S from the hot product gases using limestone generates calcium sulfide, a potentially hazardous chemical requiring treatment before disposal. One approach is to convert the CaS to CaSO 4 via oxidation in a topping cycle pressurized fluidized bed combustion. In this work, the oxidation behavior of sulfided limestone particles was examined under the conditions of pressurized fluidized bed combustion using a pressurized thermogravimetric analyzer. Experiments were conducted ensuring that the partial pressure of CO 2 in the reaction gas mixtures exceeded the equilibrium pressure for CaCO 3 calcination. The effects of total pressure, O 2 partial pressure and temperature were examined to determine their influence on the conversion of CaS to CaSO 4 and on the amount of CaCO 3 formed during the oxidation process. The total pressure was shown to have only a relatively weak influence on the degree of conversion to sulfate, in spite of the fact that the conversion of CaS to CaSO 4 increased to a certain extent with increasing pressure at a constant oxygen volume fraction. However, over the 0.1-2.0 MPa range, temperature had a strong influence on the CaS oxidation, its effect being more pronounced at lower pressures. Furthermore, the reaction of CaS with CO 2 occurred above 550ЊC and the solid product was primarily CaCO 3 .